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Replace the tcp_buffers memory pool with static per-loop buffer

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As a single thread can process only one TCP send at the time, we don't
really need a memory pool for the TCP buffers, but it's enough to have
a single per-loop (client manager) static buffer that's being used to
assemble the DNS message and then it gets copied into own sending
buffer.

In the future, this should get optimized by exposing the uv_try API
from the network manager, and first try to send the message directly
and allocate the sending buffer only if we need to send the data
asynchronously.
This commit is contained in:
Ondřej Surý
2024-06-04 08:38:35 +02:00
committed by Nicki Křížek
parent 982eab7de0
commit 452a2e6348
2 changed files with 8 additions and 32 deletions
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35
lib/ns/client.c
View File

@@ -376,7 +376,7 @@ static void
client_setup_tcp_buffer(ns_client_t *client) {
REQUIRE(client->tcpbuf == NULL);
client->tcpbuf = isc_mempool_get(client->manager->tcp_buffers);
client->tcpbuf = client->manager->tcp_buffer;
client->tcpbuf_size = NS_CLIENT_TCP_BUFFER_SIZE;
}
@@ -386,13 +386,12 @@ client_put_tcp_buffer(ns_client_t *client) {
return;
}
if (client->tcpbuf_size == NS_CLIENT_TCP_BUFFER_SIZE) {
isc_mempool_put(client->manager->tcp_buffers, client->tcpbuf);
} else {
if (client->tcpbuf != client->manager->tcp_buffer) {
isc_mem_put(client->manager->send_mctx, client->tcpbuf,
client->tcpbuf_size);
}
client->tcpbuf = NULL;
client->tcpbuf_size = 0;
}
@@ -440,21 +439,14 @@ client_sendpkg(ns_client_t *client, isc_buffer_t *buffer) {
if (isc_buffer_base(buffer) == client->tcpbuf) {
size_t used = isc_buffer_usedlength(buffer);
const size_t threshold = (3 * NS_CLIENT_TCP_BUFFER_SIZE) / 4;
INSIST(client->tcpbuf_size == NS_CLIENT_TCP_BUFFER_SIZE);
/*
* Copy the data into a smaller buffer before sending,
* and keep the original big TCP send buffer for reuse
* by other clients.
*/
if (used > threshold) {
/*
* The data in the buffer is very large, so there is
* no point in using a smaller buffer.
*/
r.base = buffer->base;
} else if (used > NS_CLIENT_SEND_BUFFER_SIZE) {
if (used > NS_CLIENT_SEND_BUFFER_SIZE) {
/*
* We can save space by allocating a new buffer with a
* correct size and freeing the big buffer.
@@ -1728,8 +1720,6 @@ ns__client_put_cb(void *client0) {
client->magic = 0;
isc_mem_put(manager->send_mctx, client->sendbuf,
NS_CLIENT_SEND_BUFFER_SIZE);
if (client->opt != NULL) {
INSIST(dns_rdataset_isassociated(client->opt));
dns_rdataset_disassociate(client->opt);
@@ -2437,9 +2427,6 @@ ns__client_setup(ns_client_t *client, ns_clientmgr_t *mgr, bool new) {
client->manager->rdspool,
DNS_MESSAGE_INTENTPARSE, &client->message);
client->sendbuf = isc_mem_get(client->manager->send_mctx,
NS_CLIENT_SEND_BUFFER_SIZE);
/*
* Set magic earlier than usual because ns_query_init()
* and the functions it calls will require it.
@@ -2460,7 +2447,6 @@ ns__client_setup(ns_client_t *client, ns_clientmgr_t *mgr, bool new) {
*client = (ns_client_t){
.magic = 0,
.manager = client->manager,
.sendbuf = client->sendbuf,
.message = client->message,
.query = client->query,
};
@@ -2485,8 +2471,6 @@ ns__client_setup(ns_client_t *client, ns_clientmgr_t *mgr, bool new) {
return (ISC_R_SUCCESS);
cleanup:
isc_mem_put(client->manager->send_mctx, client->sendbuf,
NS_CLIENT_SEND_BUFFER_SIZE);
dns_message_detach(&client->message);
ns_clientmgr_detach(&client->manager);
@@ -2514,8 +2498,6 @@ clientmgr_destroy_cb(void *arg) {
dns_message_destroypools(&manager->rdspool, &manager->namepool);
isc_mempool_destroy(&manager->tcp_buffers);
isc_mem_detach(&manager->send_mctx);
isc_mem_putanddetach(&manager->mctx, manager, sizeof(*manager));
@@ -2607,13 +2589,6 @@ ns_clientmgr_create(ns_server_t *sctx, isc_loopmgr_t *loopmgr,
*/
(void)isc_mem_arena_set_muzzy_decay_ms(manager->send_mctx, 0);
isc_mempool_create(manager->send_mctx,
(size_t)NS_CLIENT_TCP_BUFFER_SIZE,
&manager->tcp_buffers);
isc_mempool_setfillcount(manager->tcp_buffers, TCPBUFFERS_FILLCOUNT);
isc_mempool_setfreemax(manager->tcp_buffers, TCPBUFFERS_FREEMAX);
isc_mempool_setname(manager->tcp_buffers, "ns_clientmgr_tcp");
manager->magic = MANAGER_MAGIC;
MTRACE("create");

5
lib/ns/include/ns/client.h
View File

@@ -159,7 +159,7 @@ struct ns_clientmgr {
isc_mutex_t reclock;
client_list_t recursing; /*%< Recursing clients */
isc_mempool_t *tcp_buffers;
uint8_t tcp_buffer[NS_CLIENT_TCP_BUFFER_SIZE];
};
/*% nameserver client structure */
@@ -180,7 +180,6 @@ struct ns_client {
unsigned char *tcpbuf;
size_t tcpbuf_size;
dns_message_t *message;
unsigned char *sendbuf;
dns_rdataset_t *opt;
dns_ednsopt_t *ede;
uint16_t udpsize;
@@ -230,6 +229,8 @@ struct ns_client {
* bits will be used as the rcode in the response message.
*/
int32_t rcode_override;
uint8_t sendbuf[NS_CLIENT_SEND_BUFFER_SIZE];
};
#define NS_CLIENT_MAGIC ISC_MAGIC('N', 'S', 'C', 'c')